Comand aps NTG 2.5 for B170 -year 2006
 

I have just the basic radio system without navi system or bluetooth on my wifes B 170 -2006. Now I plan to buy Comand APS NTG 2.5 HDD for it, with parking camera. Does anybody know that what is best, cheapest but safe place to buy this system? And what other accessories are needed, adaptors or cables etc? Thanks a lot for help